Method of making sheet metal fasteners



Se t. 25, 1962 E. B. FERNBERG 3,055,103

METHOD OF MAKING SHEET METAL FASTENERS Original Filed Oct. 2. 1957 2Sheets-Sheet l Sept. 25, 1962 E. B. FERNBERG METHOD OF MAKING SHEETMETAL FASTENERS 2 Sheets-51199122 Original Filed 001:. 2. 1957 Thisinvenn'on relates to sheet metal fasteners but more particularly to themanufacture of such features.

An object is to produce a simple and efiicient method of producingfasteners from a single strip of sheet metal in such manner that asubstantial saving of material is effected as compared to currentmethods; resilient characteristics are selectively imparted to theultimate fastener in a novel manner; and difierent size fasteners can beproduced from a starting piece of the same width of sheet metal.

By way of illustration but not of limitation, embodiments of theinvention are shown on the accompanying drawings in which:

FIGURES 1, 2 and 3 show three stages in shaping a blank to form afastener;

FIGURES 4, 5, 6 and 7 are respectively a plan, front and side elevationand perspective view of the fastener formed from the blank of FIGURES 1to 3, and

FIGURES 8 to 11 are illustrations of modifications of theinventiomFIGURE 11 being a section on the line A-A of FIGURE 10.

At 29 in FIGURE 1 is shown a blank in the form of a rectangular strip ofsteel out of which has been punched an elongate hole 21. The hole liesalong the length of the strip and is wider at one end 22 than the other.The hole leaves two arms 23 and 24- and two closed ends 25 and 26.

As shown in FIGURE 2, the next step in the process is, simultaneously orin sequence, to force apart the two arms 23 and 24, shear out the armsat the right hand end to the shape shown, and twist the arms.

The sheared-out right-hand end of the strip is to constitute asnap-engaging stud portion of the final fastener and henceforththerefore will be called a stud 26, having a closed nose 27 and twolimbs 28 and 29.

The left-hand end of the strip is to constitute a base 30 of thefinished fastener.

It will be seen that the arms 23 and 24 have maximum displacement atabout the line 31, the original shape of the rectangular blank beingshown in broken lines.

The two arms 23 and 24 are twisted in opposite senses. Those portions ofthe arms constituting the stud-limbs 28 and 29 have their inside edgespushed up from the plane of the paper, with respect to the outer edges,so that the narrow inside edges can be seen at 2% and 29' in the planview of FIGURE 2.

Those portions of the arms 2-3 and 24- which lie in the base portion 30adjacent the line 31, have their outside edges twisted upwardly from theplane of the paper.

The next step is illustrated in FIGURE 3. Here the twist of the studlimbs 28 and 29 has been increased until intermediate portions of thelimbs are in approximately parallel planes which are perpendicular tothe plane of the paper. Thus in the plan view of FIGURE 3 only the edges28 and 29 can be seen at these intermediate positions. The two limbshave also been formed with opposed outwardly directed snap-engagingelbows 32 and 33, whilst the temporary twist in the arms 23 and 24- hasbeen removed so that these portions are again flat and in the plane ofthe paper.

3,055,193 Patented Sept. 25, 1962 The strip is then bent, approximatelyat right angles, in the neighborhood of the transverse line 31 so thatthe stud 26 stands perpendicular to the base 30. Finally the base isbent twice at approximately right angles into the shape of a hook.

The final shape of the fastener is illustrated in FIG- URES 4 to 7.After being thus formed the fastener is preferably rendered resilientand rust-proof in any convenient manner.

It can be seen that the hole 21 extends into the base 30 and around theweb thereof. This feature of the fastener ensures high resiliency in thestud portion.

The resiliency of the stud is also enhanced by the bend in the nose 2 7of the stud, this bend being about a line parallel with the planecontaining the limbs of the stud.

The fastener may be used, in well known manner, to hold one member, suchas a trim pad, to an apertured panel, the hook engaging an edge of (or ahole in) the pad and the stud snapping through the aperture in thepanel.

Four important advantages accrue to the fastener described and itsmethod of manufacture.

The first is that a very large saving of material is achieved as aresult of the forcing apart of the limbs. One may start with a strip ofgiven width and expand it to a width which may be up to as much as 50%greater.

The second is that the final dimensions of the stud can be adjusted byappropriately varying the extent to which the arms 23 and 24 and limbs28 and 29 are forced apart. For a large panel aperture the limbs areforced further apart and for a small one are pushed only a little wayapart.

Thus fasteners accommodating a range of panel aperture sizes can beproduced from starting strip of the same width. The finished fastenersare usually wider than the starting strip.

The third advantage is that not only does the presence of the elongatehole afiord great resilience in the fastener, but by choice of thelength of the hole, the resilience can be adjusted.

The fourth advantage is similar to the first and arises from the bend inthe nose 27 of the fastener, this bend increasing the resilience whichcan be given to the fastener.

In FIGURE 8 is shown a modified fastener in which the limbs have notbeen forced apart, but in which a bend 34 in the nose of the fastener isformed about a line 3-5 inclined a little to the plane containing thelimbs. Nevertheless, the line about which bending occurs remains veryapproximately parallel to this plane. The elbow is formed in one limbonly, and shoulders are formed at the roots of the l mbs to limit thedistance by which the stud enters a panel aperture.

As shown in FIGURE 9 the line 36 about which the bend 37 in the noseoccurs is curved, remaining, however, approximately parallel to theplane containing the limbs.

The fastener illustrated in FIGURES 1-0 and 11 has a bend 38 in the nosesimilar to that of FIGURE 8 and in addition has those portions 39 and46' of its arms lying in the stud twisted, in opposite senses, so thattheir inner edges are higher than their outer edges. The bend in thenose and the twist of the arms both increase the resilience of thefastener.

The bend in the nose of the fastener may be either convex or concave.Similarly the limbs of the fastener may have their bends of oppositesense to that described above.

This application constitutes a division of my copending applicationSerial No. 687,674, filed October 2, 1957 now Patent No. 2,966,711 andentitled Fasteners.

ice

What I claim is:

1. A method of making a one-piece snap fastener from a blank in the formof a single strip of flat material, comprising the steps of forming inthe strip an elongate hole lying along the length of the strip so as toform two arms of material joined at their ends, increasing the distancebetween the two arms over at least an intermediate portion of theirlengths to form at least one external elbow on one of the arms, bendingthe strip about a transverse line offset from the elbow so that oneportion containing the elbow forms a snap-engaging stud and the otherportion forms a base, and twisting the arms constituting the stud inopposite senses through approximately 90, and bending the arms to formin the finished stud opposed outwardly directed snap-engaging elbows.

2. A method of making a one-piece snap fastener from a blank in the formof a single strip of flat material, comprising the steps of forming inthe strip an elongate hole wlider at one end lying along the length ofthe strip so as to form two arms of material joined at their ends,increasing the distance between the two arms and bending the strip abouta transverse line so that the portion having the wider portion of thehole forms a resilient stud and the other a base, and twisting the armsconstitutling the stud in opposite senses through approximately 90.

3. A method of making a one-piece snap fastener from a blank in the formof a single strip of flat material, comprising the steps of forming inthe strip an elongate hole lying along the length of the strip so as toform two arms of material joined at their ends, increasing the distancebetween the two arms and bending the strip about a transverse line sothat one portion forms a resilient stud and the other a base, twistingthe arms constituting the stud in opposite senses through approximately90, and bow-ing the closed end of the strip forming part of the studabout a line which is approximately parallel with the plane of thestrip.

References Cited in the file of this patent UNITED STATES PATENTS GreatBritain Oct. 25, 1940

